1. Field of the Invention
The present invention relates generally to a sheet feed device that includes a first sheet cassette and a second sheet cassette disposed on the first sheet cassette, and selectively feeds sheets (recording media) that are positioned in the first sheet cassette or sheets that are positioned in the second sheet cassette and are different than, e.g., smaller than, the sheets in the first sheet cassette. The present invention also relates to an image recording apparatus having such a sheet feed device.
2. Description of Related Art
A sheet feed device used in a known image recording apparatus, such as a printer and/or a facsimile machine, is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2002-249242. In this known sheet feed device, the sheet cassette for accommodating a stack of recording media (such as recording sheets and cut sheets) is disposed in a lower side of the apparatus body (housing). The sheet cassette is movable into and from the housing. A drive shaft is disposed above the sheet cassette so as to extend in a direction perpendicular to the sheet feed direction. A sheet feed arm is pivotally attached to the drive shaft, and a free end of the sheet feed arm extends toward an inclined separation plate that is provided at one end of the sheet feed cassette. A sheet feed roller is attached to the free end of the sheet feed arm, and power for rotating the sheet feed roller is transmitted from the dive shaft via a power-transmitting unit disposed at the sheet feed arm. The sheet feed roller is urged by a spring to abut the uppermost sheet surface regardless of the height of the sheets stacked in the sheet cassette.
In this known sheet feed device, the inclination angle of the sheet feed arm with respect to the uppermost sheet surface, that is, an angle formed by the uppermost sheet surface with a line between the pivot center of sheet feed arm (axial center of the drive shaft) and a point where the sheet feed roller contacts the uppermost sheet surface varies depending on the height of the sheets stacked in the sheet cassette. When the inclination angle of the sheet feed arm is smaller than a predetermined value, a force of the sheet feed roller applied to the uppermost sheet surface is insufficient to feed the uppermost sheet,